The torsion beam type rear wheel suspension system is known as a preferred wheel suspension system for small passenger vehicles because of the favorable handling of the vehicle and the space saving which this wheel suspension system provides in spite of its highly simple structure. A torsion beam type rear wheel suspension system comprises a pair of trailing arms each having a front end pivotally supported by a vehicle body for a vertical swinging movement and a rear end extending rearwardly from the front end thereof and carrying a rear wheel rotatably supported thereby, a torsion beam extending between intermediate points of the trailing arms laterally across the vehicle body and having a U-shaped cross section and a stabilizer received in a hollow interior of the torsion beam and having two ends connected to parts of the trailing arms.
The stabilizer typically consists of a torsion bar, and is desired to be properly spaced from the surrounding wall of the torsion beam so that undesired noises and wears may not be caused by the contact between the stabilizer and surrounding wall of the torsion beam. For this purpose, it has been practiced to use a stabilizer bush received in the hollow interior of the torsion beam to retain an intermediate part of the stabilizer to the torsion beam. The stabilizer bush is typically made of rubber material so as not to obstruct the torsional deformation of the stabilizer and torsion beam. Japanese patent publication No. 7-91474 and Japanese patent No. 3948388 disclose such stabilizer bushes.
An optimum result can be achieved when the stabilizer bush is placed in a laterally central part of the torsion beam in the case when only one such stabilizer bush is used. When two or more stabilizer bushes are used, they are desired to be evenly spaced from each other. However, it was found that the stabilizer bush may shift laterally in position during use, and that the pressure of water that is splashed onto the stabilizer bush often causes such a lateral shifting of the stabilizer bush.
Japense patent publication No. 2001-80332 discloses a dynamic damper provided in an intermediate part of a torsion beam of a torsion beam type wheel suspension system for the purpose of controlling the resonant vibration of the torsion beam. The dynamic damper comprises a weight, a rubber layer surrounding the weight and a bracket attached to a middle part of the torsion beam to resiliently support the weight via resilient legs integrally extending from the rubber layer.